I always give myself an extra digit than I think I'm likely to need since I do save these as presets, but I just tried selecting 11 images, telling it one digit starting with 1, and no crash. Not even any hesitation. It just cycled around when it had done with 1-9, as I would expect. Are all your filenames going to be identical if it batch renames and has to cycle around? I would have to specifically create files with identical filenames in order to test that, and I'd rather not go to the trouble if that isn't what's happening to you.

Bridge gets twitchy when you update, so if you're not at risk of naming files in a batch identically, it could be your preferences are corrupt and need to be purged.

Extra digits aren't an option for these files, as the naming convention is not mine to adjust. I've been doing it like this for years, sometimes it would get temporarily confused, today it hung permanently, twice. It's likely this is the first time I've been in this situation since updating to 2018, so that's the first place I'm looking for the problem.

It's not cycling though, it's getting stuck. When I open the folder in Finder, the offending files are still sporting their temporary names, Bridge is frozen (and using 100% CPU) and that's the way it stays.

This happened twice today. I'm working on another system tomorrow and I'll check it again on that machine.